Heart rate response to alarm tones in firefighters.

Marciniak, Rudi A; Tesch, Cody J; Ebersole, Kyle T

OBJECTIVE To examine cardiovascular responses to medical (MED) and fire (FIRE) alarm tones in firefighters. METHODS Heart rate was collected throughout 24-h shifts (N = 41). Call logs were utilized post hoc to identify heart rate at the time the alarm sounded (TIMETONE), peak heart rate following the alarm (TIMEPEAK), and heart rate at the time of station departure (TIMEDEPART) for MED and FIRE calls. A 2X3 (TONE x TIME) split-plot mixed-model repeated-measures analysis of variance (ANOVA) and least significant differences tests examined the influence of tone type on heart rate, expressed as a percent of age estimated maximum. Bivariate Pearson correlations examined the relationship between body mass index (BMI) and TIMEPEAK and TIMEDEPART. An alpha of 0.05 determined statistical significance and Bonferroni Corrections were applied to post hoc comparisons (p < 0.017). RESULTS Follow-up analyses for the significant 2 × 3 repeated-measures ANOVA (p = 0.035) indicated differences in heart rate for MED (p < 0.001) and FIRE (p < 0.001) where TIMETONE < TIMEPEAK, TIMETONE < TIMEDEPART, and TIMEPEAK > TIMEDEPART. There was a non-significant simple effect of time for MED and FIRE at TIMETONE (p = 0.259), but significant effects of tone type where FIRE > MED at TIMEPEAK (p < 0.001) and TIMEDEPART (p = 0.002). There was a significant small positive relationship between BMI and TIMEPEAK (p = 0.002) and TIMEDEPART (p < 0.001) for MED only. CONCLUSIONS Alarms increased heart rates to a greater extent in FIRE than MED calls. Higher BMI was related to greater heart rate responses in MED but was unrelated to FIRE response.